1. Field of the Invention
The present invention relates to medical catheters. More specifically, the invention relates to pushable balloon-tipped catheters and a method for making the balloon catheter.
2. Background
Pushable balloon-tipped catheters are used for the treatment of many conditions relating to body vessels including arteries and veins. For such treatments, a wire guide may be percutaneously inserted into the body vessel and positioned near a location where treatment is necessary. The balloon catheter may be inserted through a guide catheter over the wire guide. The distal tip of the balloon catheter is guided to the treatment location along the wire guide. Once at the treatment location, the balloon at the distal tip of the catheter is unfolded and inflated, such as for example, by pumping a mixture of saline and/or contrast solution through the catheter into the balloon. When inflated, the balloon presses against the inner wall of the body vessel to dilate the vessel. If a stent is mounted on the balloon, inflation of the balloon will also expand the stent to implant the stent within the artery. After the vessel is dilated, the balloon is deflated to collapse the balloon back onto the shaft of the catheter for retraction into the guide catheter and retrieval from the body vessel.
Sometimes difficulties may be encountered in retracting the deflating balloon back into the guide catheter. These difficulties may be attributed to various factors, such as for example, the shape of the balloon, incomplete deflation of the balloon, and/or the balloon not returning to its initial folded condition after deflation. Consequently, the force required to retract the balloon into the guide catheter may be unacceptably and/or undesirably high. Moreover, there may also be a risk that the balloon will get caught against the distal end of the guide catheter, making it difficult to remove the balloon catheter from the treatment site.
Current methods for resolving some of these difficulties have been to design balloon catheters with thinner, weaker balloon walls. Generally, a balloon having a thinner, weaker wall will present fewer difficulties on retraction from the body vessel than a balloon of the same shape having a thicker, stronger wall. However, the strength of a balloon wall, and more particularly the burst strength of the balloon wall, is a critical design parameter that may make reducing the balloon wall thickness impractical for lowering the force necessary to retract the balloon.